On Wed, Nov 11, 2020 at 11:09:13PM +1100, Anand K. Mistry wrote:
> Hi,
>
> I'm requesting a stable merge for commit
> 1978b3a53a74e3230cd46932b149c6e62e832e9a
> ("x86/speculation: Allow IBPB to be conditionally enabled on CPUs with
> always-on STIBP")
> into the stable branch for 5.4. Note, the commit is already queued for
> inclusion into the next 5.9 stable release
> (https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/tree/queue-5.9/x86-speculation-allow-ibpb-to-be-conditionally-enabl.patch).
>
> The patch fixes an issue where a Spectre-v2-user mitigation could not
> be enabled via prctl() on certain AMD CPUs. The issue was introduced
> in commit 21998a351512eba4ed5969006f0c55882d995ada
> ("x86/speculation: Avoid force-disabling IBPB based on STIBP and
> enhanced IBRS.")
> which was merged into the 5.4 stable branch as commit
> 6d60d5462a91eb46fb88b016508edfa8ee0bc7c8. This commit also exists in
> 4.19, 4.14, 4.9, and 4.4, so those kernels are also likely affected by
> this bug.
As I asked when I sent out a "FAILED:" message for this patch, if
someone wants it backported to older kernels, they will need to provide
the backported versions of it, as the patch does not apply cleanly
as-is.
Can you please do that?
thanks,
greg k-h
